As is evident from a review of the relevant patent, scientific and industrial literature, consistently achieving a desired extended drug release profile can be rather difficult. Factors that can influence the extended release profile of a tablet include the physical and chemical characteristics of the pharmaceutically active ingredient, patient-to-patient variability in the physiological environment in which the drug is released, variability in the temporal physiological environment in the which the drug is released for an individual patient, the nature of the inactive ingredient selected for preparing the tablet, and the manner in which the ingredients are processed and combined to prepare the tablet.
Even the amount of pressure used during tablet compression can influence tablet hardness, which can in turn have a profound effect on the drug release profile. Accordingly, once an effective tablet preparation procedure has been established for achieving a desired extended drug release profile for a particular pharmaceutically active ingredient, great care is normally taken to ensure that the procedure is precisely duplicated for each production run to avoid variation in the drug release profile due to variations in the properties of the tablet.
It would be desirable to eliminate, or at least reduce, the effect of tablet hardness on drug release rate, such as to facilitate production of different types of tablets from the same or similar formulation. For example, if the effects of tablet hardness on the drug release profile could be eliminated or significantly reduced, it may be possible to prepare, from identical or very similar formulations, chewable and swallowable tablets having different hardnesses, but the same or very similar drug release profiles. Eliminating or substantially reducing the effect of tablet hardness on drug release profile is also beneficial for production of a single tablet type, since it reduces the potential for variation in the release profile from one production batch to another.